Good as Gone (Simon Fisk #1) by Douglas Corleone

SIMON FISK, HAUNTED BY HIS DAUGHTER'S DISAPPEARANCE, INVESTIGATES A CHILD ABDUCTION WHICH BECOMES AN INTERNATIONAL HUNT.

Former U.S. Marshal Simon Fisk works as a private contractor, tracking down and recovering children who are kidnapped by their estranged parents. He only has one rule: he won't touch stranger abduction cases. He's still haunted by the unresolved disappearance of his six-year-old daughter, and non-family kidnappings hit too close to home.

Until, that is, another six-year-old, Lindsay Sorkin, disappears from her parents' hotel room in Paris, and the French police deliver Simon an unltimatum: he can spend years in a French jail for past misdemeanors, or he can take the case and recover the missing girl. Simon sets out in pursuit of Lindsay and the truth behind her disappearance. But Lindsay's captors have not left an easy trail, and following it will take Simon across the continent, through the ritziest nightclubs and the seediest back alleys, into a terrifying world of international intrigue and dark corners of his past he'd rather leave well alone.